dV remaining during flight? (KER not available?)

[Shaamaan]

I'm new to KSP, albeit I think I got the basics of... things. Anyway, people keep saying KER is a must-have, so I gave it a go. And, sure enough, it has plenty of info during the building stage in KSP. However, when I'm actually in-flight (or even stationary at the launch pad), the KER button is darker and seems to be not available.

It would be a massive help to know the remaining dV I have. Thus far I need to eyeball it, which is usually OK (I tend to over-engineer a bit anyway), but on a few occasions where I messed up a planned manoeuvrer I could REALLY use this... Does KER not have this information? Or am I just not accessing this info correctly?

 

EDIT: Dear administrator - I've figured it out. KER has a setting where I either need to put in an additional module on my rocket, or toggle the setting off. Feel free to delete this message once you get to moderating it.

Sincerely,
Shaamaan

Edited April 17, 2018 by Shaamaan

[Tyko]

In the VAB you can change the KER Settings so that you no longer need that additional part. 

[artwhaley]

Darn... figured it out before I got here with my obnoxious answer.  

Oh, DeltaV is easy!   Go ahead and grab 2 or 3 sheets of paper... then write down the wet and dry mass of every tank... and the isp of every engine... and then....